This document was obtained by Wikileaks from the United States Congressional Research Service.

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Daylight Saving Time (DST) is currently observed in the United States from 2:00 a.m. on the second Sunday in March until 2:00 a.m. on the first Sunday in November. The following states and territories do not observe DST: Arizona, Hawaii, American Samoa, Puerto Rico, and the Virgin Islands.

Daylight Saving Time (DST) is currently observed in the United States from 2:00 a.m. on the second Sunday in March until 2:00 a.m. on the first Sunday in November. The following states and territories do not observe DST: Arizona, Hawaii, American Samoa, Puerto Rico, and the Virgin Islands. This report will be updated as needed.

Daylight Saving Time (DST) is not a new concept. In 1784, when Benjamin Franklin was Minister to France, an idea occurred to him: in that part of the year when the sun rises while most people are still asleep, clocks could be reset to allow an extra hour of daylight during waking hours. He calculated that French shopkeepers could save one million francs per year on candles. In 1907, William Willett, a British builder, Member of Parliament, and fellow of the Royal Astronomical Society, proposed the adoption of advanced time. The bill he introduced was reported favorably, asserting that DST would move hours of work and recreation more closely to daylight hours, reducing expenditures on artificial light. There was much opposition, however, and the idea was not adopted.

During World War I, in an effort to conserve fuel, Germany began observing DST on May 1, 1916. As the war progressed, the rest of Europe adopted DST. The plan was not formally adopted in the United States until 1918. “An Act to preserve daylight and provide standard time for the United States” was enacted on March 19, 1918 (40 Stat 450). It established both standard time zones and set summer DST to begin on March 31, 1918. The idea was unpopular, however, and Congress abolished DST after the war, overriding President Woodrow Wilson’s veto. DST became a local option and was observed in some states until World War II, when President Franklin Roosevelt instituted year-round DST, called “War Time,” on February 9, 1942. It lasted until the last Sunday in September 1945. The next year, many states and localities adopted summer DST.

By 1962, the transportation industry found the lack of nationwide consistency in time observance confusing enough to push for federal regulation. This drive resulted in the Uniform Time Act of 1966 (P.L. 89-387). The act mandated standard time within the established time zones and provided for advanced time: clocks would be advanced one hour beginning at 2:00 a.m. on the last Sunday in April and turned back one hour at 2:00 a.m. on the last Sunday in October. States were allowed to exempt themselves from DST as long as the entire state did so. If a state chose to observe DST, the time changes were required to begin and end on the established dates. In 1968, Arizona became the first state to exempt itself from DST. In 1972, the act was amended (P.L. 92-267), allowing those states split between time zones to exempt either the entire state or that part of the state lying within a different time zone. The newly created Department of Transportation (DOT) was given the power to enforce the law. Currently, the following states do not observe DST: Arizona, Hawaii, American Samoa, Puerto Rico, and the Virgin Islands.

During the 1973 oil embargo by the Organization of Petroleum Exporting Countries (OPEC), in an effort to conserve fuel Congress enacted a trial period of year-round DST (P.L. 93-182), beginning January 6, 1974, and ending April 27, 1975. From the beginning, the trial was hotly debated. Those in favor pointed to the benefits of increased daylight hours in the winter evening: more time for recreation, reduced lighting and heating demands, reduced crime, and reduced automobile accidents. The opposition was concerned about children leaving for school in the dark. The act was amended in October 1974 (P.L. 93-434) to return to standard time for the period beginning October 27, 1974, and ending February 23, 1975, when DST resumed. When the trial ended in 1975, the country returned to observing summer DST (with the aforementioned exceptions).

DOT, charged with evaluating the plan of extending DST into March, reported in 1975 that “modest overall benefits might be realized by a shift from the historic six-month DST (May through October) in areas of energy conservation, overall traffic safety and reduced violent crime.” However, DOT also reported that these benefits were minimal and difficult to distinguish from seasonal variations and fluctuations in energy prices.

Congress then asked the National Bureau of Standards (NBS) to evaluate the DOT report. In an April 1976 report to Congress, Review and Technical Evaluation of the DOT Daylight Saving Time Study, NBS found no significant energy savings or differences in traffic fatalities. It did find statistically significant evidence of increased fatalities among school-age children in the mornings during the four-month period January-April 1974 as compared with the same period (non-DST) of 1973. NBS stated that it was impossible to determine, what if any of this increase was due to DST. When this same data was compared between 1973 and 1974 for the individual months of March and April, no significant difference was found for fatalities among school-age children in the mornings.

In 1986, the 99th Congress enacted P.L. 99-359, which amended the Uniform Time Act, by changing the beginning of DST to the first Sunday in April and having the end remain the last Sunday in October.

In 2005, the 109th Congress enacted P.L. 109-58, the Energy Policy Act of 2005. Section 110 of this act amended the Uniform Time Act, by changing the beginning of DST to the second Sunday in March and changing the ending date to the first Sunday in November. The act requires the Secretary of Energy to report to Congress, within nine months of the March 2007 effective date, on the impact of this section on energy consumption in the United States. Congress retains the right to revert DST back to the 2005 time schedules once the department study is complete.

Under the Standard Time Act of 1918, as amended by the Uniform Time Act of 1966, moving a state or an area within a state from one time zone to another requires a regulation issued by the Department of Transportation (DOT). The governor or state legislature makes the request for a state or any part of the state; the highest elected officials in the county may make a request for that county. The standard in the statute for such decisions is the convenience of commerce in that area. The convenience of commerce is defined broadly to consider such circumstances as the shipment of goods within the community; the origin of television and radio broadcasts; the areas where most residents work, attend school, worship, or receive health care; the location of airports, railway, and bus stations; and the major elements of the community’s economy.

After receiving a request DOT will then determine whether it meets the minimum statutory criteria before issuing a notice of proposed rulemaking, which will solicit public comment and schedule a public hearing. Usually the hearing is held in the area requesting the change so that all affected parties can be represented. After the close of the comment period, the comments are reviewed and appropriate final action taken. If the Secretary agrees that the statutory requirement has been met, the change is instituted, usually at the next changeover to or from DST.

Under the Uniform Time Act, moving an area on or off DST is accomplished through legal action at the state level. Some states require legislation while others require executive action such as a governor’s executive order. Information on procedures required in a specific state may be obtained from that state’s legislature or governor’s office. Although it may exempt itself, if a state decides to observe DST, the dates of observance must comply with federal legislation.